Plinko Game

Main Question or Discussion Point

Me and my group for our class are planning on making a can crusher for our project. What makes ours so unique is the ending, Plinko game. We are trying to make a Plinko game out of the can after its ejected from the crusher. My part of the project is the Plinko game. My group suggested that we light up the "pegs"/"posts" in the plinko to light up(LEDs) every time a can crosses the "posts" / "pegs."
Since the can is going to touch these posts, why not make the posts out of some conductive material. If the aluminum can hits it, it can send a signal to light up the LED. We later found out that the paint on the can makes the aluminum non conductive.
Could any of you guys help suggest alternatives to how we can make the LEDs light up every time a can crosses the posts? The plinko board 6 lines in height and to 5 different "scores" in width. If additional information is required, I can try providing you as much detail as possible.

We decided to use photo-resistors to detect light, kinda like what Baluncore suggested.
What do you guys think about the wood material that we could use? Since its not a big game board, any ideas for lightweight but sturdy and also cheap materials to build it on?

Take a look around local industry for used plywood from shipping packaging. That way you are also recycling the packaging. If you paint it then it will be weather proof and so material does not matter.

If you put the LDR just above each pin you can sound a musical note whenever a pin is hit. Those notes could be tuned to sound over one octave and people may recognise the random tunes being played.